Intermixing syringe



Sept. 2, 1969 B. SCHWARTZ INTERMIXING SYRINGE Filed June 12. 1967 2Sheets-Sheet 1 INVENTOR.

501%" SCHWARTZ B Y 7 AGE/v77 Sept. 2, 1969 SCHWARTZ 3,464,412

INTERMIXING SYRINGE Filed June 12. 1967 2 Sheets-Sheet 2 80 r /O i mx IT L -Ull-'.!l.'..'.!.

INVENTOR. BORIS SCHWARTZ United States Patent 3,464,412 INTERMIXINGSYRINGE Boris Schwartz, 400 Park Ave., Paterson, NJ. 07504 Filed June12, 1967, Ser. No. 645,264 Int. Cl. A61m 5/00; A61j l/00; B67d 5/42 US.Cl. 128-218 9 Claims ABSTRACT OF THE DISCLOSURE A syringe combinationhaving an outer housing and a hollow plunger providing a pair ofchambers of determined size. The plunger is provided with a pistonhaving a plurality of spaced, ring-like sealing surfaces and with afluid passage-way from the interior of the plunger which isflow-connected to the outer piston surface and between ring-like sealingsurfaces. The outer housing has one or more recesses of determined sizeformed in its inner surface with the recesses positioned near the openend of the housing and of a length so that the rearmost sealing surfaceof the plunger piston engages the housing between the recesses and therear end of the housing when the flow-connection is brought into a fluidconducting position with the recess.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to the general class of surgery and more particularly to thesubclass of syringes.

Description of the prior art Syringes are well known in the generalfield of surgery and those for storing and intermixing variousingredients are represented in patents as to Pierick, U .8. Patent No.3,279,654 of October 1966; to Brown, US. Patent No. 2,591,046 of April1952, and to Camber, Great Britain No. 746,057 of January 1959. Theseand other patents use gravity to induce a flow from one chamber toanother. This method of transfer is often uncertain and sometimes isincomplete or requires an exact manipulation by the user who may nothave the required skill or training. The precise and exact mixing of thevarious components comprising some of the new medicants is an absolutenecessity. Ease of mixing by any potential administrator of the medicantis necessary and desirable, and an easily manipulative device is anobject of this invention.

The syringe of present invention provides a means for bringing theinterior of the housing of the syringe into a condition of reducedpressure, whereupon as a flow-conducting portion of a piston of a hollowplunger is brought into a fluid passing or mixing position, the fluidwhich is preferably stored in the plunger is sucked from the plungerinterior to flow to the housing chamber for a controlled mixing of thestored ingredients.

SUMMARY OF THE INVENTION This invention provides a syringe-typeapparatus having an outer housing of generally tubular constructionwhich is formed with an open end and a closed end. This closed end hasan aperture or passageway for the passage of medicants and the likewhich is usually to and through a needle. The plunger is slidable in thebore of the housing and is formed with a hollow interior and has one endprovided with a piston having a fluid-flow passageway extending frombetween a pair of ring-type sealing surfaces and to the interior of theplunger. The inner surface of the barrel portion of the outer housinghas formed therein at least one recess of a determined length, width anddepth and adapted to provide a fluid passageway from the interior of theplunger to and around one of the sealing rings and thence to theforeportion of the housing.

In one embodiment of this invention the syringe is arranged as anintermixing syringe in which one ingredient is stored in the foreportionof the housing and another and preferably fluid ingredient is stored inthe hollow plunger portion. In a modification of the intermixingsyringe, the outer plunger portion is provided with a resilient bulb endso that the after mixing of the ingredients the syringe may be used as amedicant dropper. In use, in either of the above embodiments, theforeportion of the housing is sealed so that as the plunger is movedoutwardly the pressure in the housing foreportion is caused to bereduced.

The two ring-type sealing surfaces between which one end of thefluid-flow passageway is terminated are at the forward or inner end ofthe plunger. Extending rearwardly from the second ring surface is apiston portion preferably having at least one more ring or formed as acontinuation of the second ring. This sealing surface rearwardly of thesecond ring is preferably of a length great enough so that as thissealing means is moved across the recess in the housing the fluid-flowportion of the piston is sealed from passing rearwardly of the sealingmeans and out of the housing. The arrangement of the sealing surfaces onthe plunger piston is made of a length great enough so that when theinnermost ring is brought into a fluid-flow condition with the recess inthe housing the remaining sealing surfaces seal the housing bore so asto prevent flow of fluid or atmosphere to and from the open end of thehousing to the plunger interior or to the foreportion of the housing.

In yet another embodiment of the invention the syringe is intended to beused as a vacuum container in which the hollow plunger portion is a testtube which may be furnished with small predetermined quantities ofvarious blood treating fluids stored in the test tube. By manipulation,the test tube or plunger and the interior of the housing is caused to bebrought into a condition of reduced pressure after which the plunger inthe reduced pressure condition is moved to a storing position afterwhich the interior of the housing is opened to the atmosphere to bringthe interior of the housing to atmospheric pressure. At the time of use,the fore-end or closed end of the housing has a needle mounted on a hubportion.

The apparatus with the needle attached is used as a syringe to withdrawa blood sample from the patient and to secure and store a determinedquantity of blood within the syringe. After the desired amount of bloodis drawn into the housing, the syringe is manipulated to draw the bloodinto the test tube. When the transfer of the blood to the test tube iscompleted the needle is discarded and the test tube is moved fully intothe housing for shipment to the laboratory. At the time the blood sampleis to be tested, the housing and the piston are discarded and the testtube with the blood therein is tested or treated in the usual manner.

It is an object of this invention to provide an intermixing syringeassembly in which two or more medicants are isolated for storage andwhich at a determined time and by manipulative action are mixedimmediately prior to the use thereof. The intermixing of the componentsis provided when the plunger is manipulated to move the plungeroutwardly so that the housing is brought into a condition of reducedpressure after which the piston of the syringe is brought into afluid-passing position so that the fluid stored in the plunger is causedto be sucked into the reduced pressure portion of the housing portionfor agitated mixing.

It is a further object of this invention to provide an intermixingsyringe wherein the medicants may be isolated for storage and which, atthe time of mixing, the

ingredients may be brought into comingle relationship with each otherand in which the exterior end portion of the plunger is provided with aresilient bulb member adapted to act with the syringe as a medicantdropper.

It is a further object of this invention to provide a syringe apparatusin which the plunger is a test tube having a piston portion on its openend and adapted to slide within a housing so that the test tube may bebrought to a condition of reduced pressure. The closed end of thehousing is adapted to mount a needle for the drawing of blood from apatient and after the drawing of a determined quantity of blood into thehousing this blood is transferred by manipulation of the plunger intothe test tube for storage and transport.

There has been outlined rather broadly the most important features ofthe various embodiments of the syringe apparatus of this invention inorder that the present contribution to the art may be more fullyappreciated. Those persons skilled in this art will appreciate that theconcept on which the present disclosure is based may be utilized toprovide the basis for other syringe devices similarly carrying out thepurposes of this invention. The chosen embodiments of the apparatus areprovided for the purposes of illustration and description of theprinciples of this invention and are shown in the accompanying drawingsforming a part of the specification wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 represents a sectional view ofan intermixing syringe in which the components to be mixed are shown asstored in two separated compartments or members of the syringe;

FIG. 2 represents the syringe of FIG. 1 with the components brought intomixing relationship within the housing member;

FIG. 3 represents the syringe of FIG. 1 and showing a needle attached tothe housing and the syringe after the contents have been expelledtherefrom;

FIG. 4 represents a sectional view taken on the line 44 of FIG. 1 andshowing one embodiment of a fluid bypass recess as formed in the outerhousing member;

FIG. 5 represents a sectional view through an alternate embodiment inwhich the hollow plunger is a test tube;

FIG. 6 represents a sectional view through yet another embodiment inwhich the plunger outer end is provided with a resilient bulb and theplunger and housing are adapted for mixing and for dispensing of amedicant in the manner of a dropper;

FIG. 7 represents a sectional view showing an end closure or cap formounting on the discharge end of the housing of FIG. 6;

FIG. 8 represents a side view of an outer housing with a portion of theside wall broken away to show yet another form of a fluid bypass formedin the housing inner wall;

FIG. 9 shows a fragmentary and sectional side view of the fluid bypassof FIG. 8, the view taken on the line 9-9 of FIG. 10, and

FIG. 10 shows a sectional view of the housing as taken on the line 10-10of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now particularly tothe drawings in which like numbers refer to like members throughout thevarious figures and in particular to the intermixing syringe shown inFIGS. 1 through 4, in which is shown an outer housing of conventionalconfiguration and including a reduced front end 21 sized so as to retaina needle on its outer tapered end. This housing has an open rear endwith an outer flange portion 22 providing a shoulder or stop for theusers fingers. The interior diameter of this housing 20 is substantiallyround and constant with the exception of a portion near the rear inwhich is provided a fluid bypass in the form of outwardly extendingscallops 24. These scallops are particularly seen in FIGS. 1 and 4 and,as reduced to practice, are in the form of arcuate cuts approximatelyone-quarter of an inch long and with a depth and width of one-sixteenthof an inch at their maximum. At the rear end of the housing 20 it is tobe noted that a small internal lip 25 is formed in order to provide alimit means or stop for the outward movement of a plunger member 30.

Referring now to the movable plunger member generally identified as 30,it is to be noted that a generally tubular portion 31 has a reducedfront end upon which is fitted a piston plunger preferably of rubber andidentified as 32. This piston plunger, in the preferred instance, isformed with three outwardly extending like-sized resilient ring-likeportions 33. Between the front first and second ring-like portions 33there is formed a fluid passageway 34 extending from the inner portionof the plunger to and through the outer peripheral surface of thepiston.

At the open or rearward end of the plunger 30 (as seen in FIG. 1) thereis carried a movable piston 35 slidable within the interior diameter ofthe barrel 31. This piston is sized to provide a fluid tight slip fitand, in the present instance, is formed with two outwardly extendingring portions adapted to provide a fluid sealing means as well assliding surfaces. At the rear end of the tubular portion 31, it is to benoted that there is a small internal shoulder or lip 36 provided toprevent or limit the unwanted outer movement of the piston 35.

It is also to be noted that the rear end of the plunger 30 is providedwith a small grasping flange 38 for the easy gripping thereof by thefingers of the operator. Still referring to FIG. 1, it is to be notedthat the reduced end of the outer housing 20 is provided with a vacuumor fluid seal in the form of a rubber or plastic plug 40 which isadapted to enter into a passageway 42 and seal this passageway both fromthe unwanted loss or entry of or plugging by powder and also to preventthe flow of air in and out of this passageway.

Referring next to FIG. 3, it is to be noted that a needle 44 is shown asmounted on the front end of the outer housing 20 after the plug 40 hasbeen removed. This needle is of standard and conventional construction.After mounting on the syringe the insertion of this needle into theflesh or vein of the patient is in the manner of conventional practice.

OPERATION OF THE INTERMIX SYRINGE Within the interior 45 of the plunger30, a determined amount of fluid 46 is stored in isolated condition andin that portion of the outer housing 20 which is forwardly of the piston32, there is stored in isolated condition a powder portion 48. Thispowder is of a determined quantity and is stored without loss inisolation and is prevented from entering and packing in the fluidpassageway 42 by means of the plug 40. In use, the interior forepart ofthe outer housing 20 identified as 49 is filled with the powder 48 of adetermined quantity and consistency.

After the powder is placed in the housing, the plunger- 30 is theninserted a determined distance into the housing as in FIG. 1. Thesealing ring portions 33 of the piston 32 after they are forwardly orinwardly of the fluid bypass 24 are sized to be in fluid tightrelationship to the inner surface of the barrel 20 so that the fluid 46which is then fed into the interior 45 of the plunger 30 for storagetherein is sealed by means of the rings 33 and, as assembled in FIG. 1,is in condition for premix storage. This syringe with the isolated fluidand powder may be shipped and stored for such period of time as isnecessary and so that those medicants having ingredients which are mixedjust prior to use may be fully mixed at that time.

To mix the fluid and powder, the plunger 30 is slowly pulled towards therear of the housing 20 so that the rearward first and second rings 33 ofthe piston 32 pass by the fluid bypass 24. It is to be noted that asthey pass by this bypass portion that two of the three rings 33 arespaced so as to always be in a housing sealing position. As the plunger30 is drawn backwardly, the interior volume of air in the housing iscaused to expand, so that a reduced pressure is developed within theinterior of the housing 20. As the midring 33 of the piston is broughtbehind the fluid bypass 24, the front ring 33 of the piston is spaced toengage or come in the way of the fluid bypass so that the interiorpassageway 34 of the piston is in flow communication with the housinginterior. The reduced pressure in the housing causes the fluid to flowfrom the plunger passageway 34 and into the forward interior of thehousing 20. This is done rapidly by means of the differential ofpressure.

In order to provide means for the fluid to rapidly flow into the powderchamber without exposing the fluid in the plunger to atmosphericpressure or to possible contamination, the freely movable piston 35 ispermitted to slide forward in the barrel of the plunger 30. This pistonis drawn forwardly to replace the fluid as the fluid is drawn into thehousing by the negative pressure induced within the outer housing.

The entire amount of fluid may be transferred rapidly in a very shorttime to instantly mix the powder and the fluid. Once the two componentshave been brought into a mingled relationship, the sealing plug 40 iswithdrawn and the needle 44 is mounted upon the reduced front end 21 ofthe tapered shank portion of the outer housing. The syringe now becomes,in effect a conventional syringe with the mixed ingredients in thehousing ready for injection in the customary manner. The plunger ismanipulated in the conventional manner to expel any air residual in thebarrel and to advance the fluid to the tip of the needle prior to theinsertion of the needle into the patient after which the entire intermixcontents may be injected into the patient.

When it is desired to cause the fluid to transfer from the plunger tothe housing at a less than rapid rate, the plunger is manipulated sothat a determined amount of recess is brought in the way of the frontsealing ring. The more area of the recess exposed to the sealing surfaceof the front seal the more rapid is the rate of transfer. As reduced topractice, the rate of transfer of fluid has been a slow flow at the rateof a mist to a maximum flow of a jet stream.

DESCRIPTION OF OTHER EMBODIMENTS Referring now to FIG. 5 and a syringein which the plunger is a test tube and in which an outer housing 60 issimilar to the housing 20 above-described, this housing 60 is formedwith a closed and reduced front end 62 sized to receive and retain aneedle, not shown, but which may be the needle 44 (FIG. 3)above-described. Within the front end of this housing is shown a plug 40as previously described which plug seals a passageway 64 within thehousing 60. The rear end of the housing is open and has a smallinternally formed lip 77 providing a stop means in the manner of lip 25above. The outer portion of the housing 60 is formed with ribs 66 and 67which provide means for easy grasping and retaining of the housing inthe hands of the user.

Within this housing there is a plunger member which, in this embodiment,includes a glass test tube 70 whose open end is closed by a rubberstopper and piston combination 72. The rear or left end portion of thestopperpiston is sized to close and seal the open end of the test tube70 while the foreportion of the piston is formed with threefluid-sealing ring portions preferably substantially equally spaced. Afluid passageway 74 is provided between the first and second rings 75reading from the right to the left as seen in the FIG. 5 and a thirdring adjacent the test tube provides an extended sealing means. Thefluid passageway extends from the interior of the test tube to the outersurface between the first and second sealing rings.

In use, the test tube 70 may have stored within it one or more fluids orother materials used for making blood determinations. Among suchmaterials are potassium oxalate; sodium heparin; lithium oxalate; sodiumoxalate; potassium oxalate and sodium fluoride; ammonium oxalate ormixtures of the above, and mineral oil may be used for otherdeterminations. The quantities and selection of material that may becombined within the test tube 70 is merely a suggestion of the variousanticoagulants or other materials used for determining blood tests.These materials are now customarily provided in measured quantities intest tubes so as to be combined with blood at the time of taking of theblood sample specimens. The test tube, of course, in many tests issterilized in the customary manner and has nothing in it and may be usedfor other tests. The storing of anticoagulants, etc., in a test tube foruse in certain test determinations is not to be implied as novel but isillustrative of one use for this embodiment.

OPERATION OF THE TEST TUBE SYRINGE It is contemplated that the syringeapparatus of FIG. 5 will be shipped assembled for use and with thestopperpiston portion 72 moved to the forward part of the outer housing60 and with the plug 40 in an air sealing relationship with thepassageway 64. Whether the test tube 70 also contains anticoagulants andthe like or not is merely a matter of selection as determined by theintended use of the syringe. Prior to the use of this assembly as asyringe the test tube is grasped and moved leftwardly until piston 72approaches the rear of the housing and the passageway 74 is brought inthe way of a fluid bypass in the housing. As the piston moves leftwardlythe air in the housing expands so that reduced pressure is developed inthe forepart of the outer housing 60. As the front ring 75 of the pistoncomes in the way of the fluid bypass, the reduced pressure in thehousing is allowed to communicate itself to the test tube 70 to providea determined vacuum or reduced pressure in the test tube. The test tubeis then pushed forward or rightwardly into the closed position, whence,as the front sealing ring is moved forwardly of the bypass, the vacuumwithin the test tube 70 is maintained. The test tube is advancedforwardly into the forward end of the housing after which the plug 40 isremoved and a needle is mounted on the reduced front end 62.

The needle may then be inserted into a vein and, in the manner of asyringe and with the test tube acting as the plunger, it is pulledrearwardly so that the piston 72 acts in a usual manner to draw bloodfrom the vein. After the desired amount of blood is drawn within theouter housing 60 the plunger is stopped and the needle is withdrawn fromthe vein. The plunger then may be moved to provide an exactdetermination of the amount of blood within the forward portion of thehousing 60, as for example, by expelling a small amount of blood throughthe needle. After the quantity of blood is provided in the housingportion, the test tube is pulled rearwardly until the passageway 74 ofthe plunger is brought in the way of the fluid bypass, whereupon thereduced pressure in the test tube causes the blood to be drawn from thehousing 60 and into the test tube 70.

After the transfer of blood from the housing to the test tube iscompleted, the piston portion and test tube is pushed forwardly withinthe container housing 60 and in this condition the test tube with theouter housing 60 acting as a shield may be transferred to the laboratoryfor the determination of the blood test. At the laboratory, with thehousing passageway 64 open, the test tube is drawn to the back end ofthe housing 60. The piston is moved past a lip 77 of the rear of thehousing and is removed therefrom with the housing 60 being discarded.

The stopper and piston portion 72 is drawn from the test tube openingand discarded after which the material in the test tube is tested in theusual manner. The test tube is preferably of conventional fire-resistantglass and after the test may be discarded.

It is to be noted in FIGS. 8, 9 and 10, that a preferred fluid bypass asformed in the outer housing is a triangular shape recess which isembossed in only one portion of the interior surface of the housing. Thehousing may be the housing 60 of FIG. with this embossure extendingabout one-quarter of an inch along the axis of the barrel and at itsbase at the rear of the housing being approximately one-quarter of aninch wide. The recess is preferably about ten or fifteen thousandths ofan inch below the normal housing bore and generally throughout thetriangular shape as shown. This fluid bypass provides the passage areagenerally necessary for the blood to be transferred from the housing tothe interior of the test tube.

This triangular shape also provides a variable passageway whereby if thetransfer to the test tube is to be very slow, the exposure of theforward ring to the triangular portion is made at the apex or forwardend which is very small. When the piston is drawn further back itsforward sealing ring portion is in the way of a larger portion of thebypass 80 and the blood or fluid will flow in a more rapid manner.

DESCRIPTION OF DROPPER-TYPE SYRINGE Referring finally to FIGS. 6 and 7,there is illustrated a modification of the syringe ofFIG. 1 wherein theforward portion of a housing 120 is provided with a male screw thread121 instead of a needle receiving shank or taper. A screw cap 122 havinga female thread portion is sized to engage and be advanced on thethreaded end of the housing to seal the housing. In this arrangement theplug 40 is dispensed with or discarded, powder may be stored within theforepart 123 of the housing and fluid may be stored in a plunger portion126 of the apparatus. It is to be noted that the rear of the plunger 126is provided with a resilient bulb or diaphragm-type member 128 which isadapted to provide a means for pushing the fluid in drops from adischarge passageway 164 of the housing 120.

OPERATION OF THE DROPPER-TYPE SYRINGE In the manner as described inconnection with the syringe of FIG. 1, the plunger 126 is pulledbackwardly to allow the fluid within the plunger to be drawn forwardlythrough the bypass and into the reduced pressure portion of thefore-housing which contains the powder. After the mixing isaccomplished, the mixed material is moved into the interior of theplunger portion. This is accomplished by causing a reduced pressure tobe induced once again in the plunger by causing a piston 130 to be drawnback to bring the piston into a flow passing position with a recess andto permit the equalizing of pressure within the two members. After thepiston is in the rearward position the screw cap is loosened to allowatmosphere to pass into the housing and, with the syringe pointedupward, the mixed material flows through the bypass into the plunger.

In certain applications it may be desirable to provide an additionalbypass at the extreme forward portion of the housing so that theplunger, after being pushed all the way forward, will be in a flowcommunication with this additional forward bypass 180 to permit a fluidflow from the plunger. To discharge a drop of mixture the resilientdiaphragm member 122 is pushed inwardly to cause a determined drop toflow through the passageway 132 of the piston 130 and into the bypassand then be discharged from the front passageway 164 in a manner of aneye dropper. With cap 122 in sealing engagement the mixed portion in thesyringe may be carried around as a sealed eye dropper without the mixedmaterial being accidentally expelled therefrom. When the screw cap isnot in place, fluid flow sealing may be provided by pulling the plungerback sufliciently to bring all of the outwardly extending rings of thepiston into sliding and sealing relationship with the outer barrelportion.

In the above-described embodiments, it is to be noted that the piston isformed with its sealing surfaces arranged so that as the piston isbrought in the way of a bypass the fluid within the interior of theplunger is sealed from flowing out the rear or open end of the housingas the piston is moved over the bypass. Transfer of fluid from thehollow plunger to the foreportion of the housing occurs only when thefluid passageway adjacent the front sealing ring is brought intoalignment with some portion of the bypass. The piston may be formed as aconstant diameter portion for the extent which is shown as between thetwo rear sealing rings. This portion may also be a series of rings. Thisrear sealing portion provides means for preventing contamination andloss of fluid rearwardly from the housing and for this reason the rearsealing portion of the piston is formed of a length suflicient to causesealing of the housing rearwardly when the piston fluid passageway isbrought in the way of any of the bypass recesses.

It is also of note that the recess is preferably spaced in the housingso that as the rear of the piston engages the retaining lip of thehousing, which lip provides an outward stop for the plunger, a maximumor near maximum fluid flow relationship is provided between the pistonand bypass.

Terms such as left, right, in, out, fore, rear and the like areapplicable to the embodiments as shown and described in conjunction withthe drawings. These terms are merely for the purpose of description anddo not necessarily apply to the various syringe embodiments shown anddescribed and the manner in which they may be constructed or used.

The conception of the remote control signal system and its manyapplications is not limited to the specific embodiment shown butdepartures therefrom may be made within the scope of the accompanyingclaims and without sacrificing its chief advantages and protection issought to the broadest extent the prior art allows.

What is claimed is:

1. An intermixing syringe for the isolated storage of at least twomedicant portions and the like, the syringe in cluding an outer housinghaving an open rear end and a partially closed front end with apassageway therethrough, and a hollow plunger having a pisto portionslidable in the bore of the housing and in its hollow portion providingfor the isolated storage of at least one of the portions, the syringeincluding means whereby at least one of the medicant portions may beselectively transferred from one of the storage positions to anotherstorage position for the mixing of the portions, the syringe havingmeans for bringing one of the storage portions into a condition ofreduced pressure, the syringe comprising: (a) an outer housing ofgenerally tubular configuration and having an inner bore of a generallyconstant cross-section and with at least one by-pass recess formed inthe inner bore, the recess of a determined Width, length and depth andpositioned at a determined distance from an open rear end of thehousing, the housing having a front partially-closed other end and apassageway therethrough; (b) means for closing the passageway of thepartially closed front end of the housing so as to prevent the passageof air, fluids and the like; (0) a plunger having a main portion ofgenerally tubular configuration and sized to easily move axially in thebore of outer housing without the sealing of the bore of the housing;(d) means providing for the closing of the rear end of the plunger andthe hollow portion thereof to the passage of air, fluid and the likewherein said means is a movable piston slideable within and throughoutthe interior bore of the plunger and providing therewith a fluid-tightsealing means, and (e) a resilient piston adapted for mounting in andclosing the front end of the plunger, said piston formed with aplurality of ring-like sealing surfaces sized so as to be slidable inthe bore of the housing while engaging said bore in a fluid-flow sealingmanner, the piston having at least one flow passage way formed thereinwith one end of the passageway opening to the interior of the plungerand the other end terminating at the piston surface and between adjacentringlike sealing surfaces, said sealing surfaces disposed and of anextent so that as the flow passageway terminating between the ring-likesurfaces of the piston is brought in the way of the bypass recess so asto permit fluid flow from the plunger through the housing bypass saidsealing surfaces of the piston that are beyond the flow passageway andadjacent the plunger main portion are disposed toward the housing openend to seal the housing and plunger from any unwanted flow of air, fluidand the like from the open end of the housing.

2. An intermixing syringe as in claim 1 in which the piston is made of alength so the axial extent of those rearwardly disposed sealing surfacesprovided between the terminating flow passageway formed betweenring-like sealing surfaces and the plunger main portion is at leastslightly greater than the axial length of the bypass recess.

3. An intermixing syringe as in claim 2 in which the rearwardly disposedsealing surfaces include at least two outwardly extending ring-likesealing surfaces normally disposed to the axis of the piston.

4. An intermixing syringe as in claim 2 in which the adjacent ring-likesealing surfaces of the piston between which the flow passagewayterminates are the forward pair of ring-like sealing surfaces of thepiston.

5. An intermixing syringe as in claim 1 in which the means for closingthe passageway in the housing front end is a resilient plug of plastic,rubber and the like, the plug having a shank portion sized for removableinsertion into and closing of said passageway, and the front end of thehousing formed with a hub portion adapted to receive and retain aneedle.

6. An intermixing syringe as in claim 5 in which the housing bore at itsopen end is formed with a small internal lip providing a stop shoulderadapted to engage the rearward ring-like sealing surface of the pistonto position the piston axially in the housing bore so as to bring theflow passageway of the piston into a flow conducting relationship withthe bypass recess in the housing, and with a small internal lip formedin the plunger bore at its outer end providing a stop for limiting theouter movement of the movable piston in the plunger bore.

7. An intermixing syringe as in claim 3 in which the bypass recess is aplurality of arcuate cuts formed in the bore of the housing.

8. An intermixing syringe as in claim 3 in which the bypass recess is atriangular shaped recess formed in the housing bore and with the base ofthe triangular shape substantially parallel to the plane of the openrear end of housing.

9. An intermixing syringe as in claim 8 in which the housing bore at itsopen rear end is provided with a small internal lip providing a stopshoulder adapted to engage the rearward ring-like sealing surface of thepiston to position the piston axially in the housing bore so as to bringthe flow passageway of the piston into flow conducting relationship withthe bypass recess in the housing.

References Cited UNITED STATES PATENTS 3,255,752 6/ 1966 Dick. 2,869,5431/1959 Ratclilf et al. 3,279,654 10/1966 Pierick. 3,348,546 10/1967Roberts et a1. l28272 RICHARD A. GAUDET, Primary Examiner M. F.MAJESTIC, Assistant Examiner US. Cl. X.R.

